Investigations On Multichannel Fluorescent Sensor Array For Discrimination Of Thiols Using Carbon Dot-Metal Ion Pairs

Thiols play vital roles in various physiological functions and life activities due to their widespread existence in many proteins and small biomolecules.Therefore,the assessment of thiols' levels is important for early diagnosis of physiological function disorders or disease states.The methods commonly used in the detection and analysis of thiols include instrumental techniques and conventional specific sensors.Instrumental techniques,including high-performance liquid chromatography,capillary electrophoresis,and mass spectrometry,could quantitatively detect and identify thiols but with drawbacks of low cost performance and complicated manipulations,so they can't be widely used in practical detection.The conventional specific sensors usually refer to fluorescence probes with high specificity for each analyte.So,the analysis of a set of analytes will need serval sensors,which is costly and time-consuming.Therefore,it is of great significance to establish a rapid,efficient and low-cost analytical method for detection of various thiols.In recent years,the sensor array became a hot spot in the research field of sensor.It integrates the functions of multiple specific sensors,and has merits of short detection time,strong ability of discrimination and simultaneous detection.This paper aims to construct a novel fluorescent sensor array for identification and detection of thiols.In chapter 1,the research background,research status and development trend of sensor arrays are briefly reviewed.The properties,synthesis and applications of carbon dots(CDs)are briefly introduced.In the chapter 2,a kind of nitrogen-doped fluorescent CDs was prepared by using citric acid and cysteine as precursor.UV-Vis absorption spectra and fluorescence spectra show that the CDs have a broad absorption peak at 345 nm and exhibit a excitation-independent PL behaviors with an excitation/emission maximum at 350/420 nm.Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy show that N was successfully doped into the CDs,X-ray diffraction patterns,transmission electron microscopy(TEM)and atomic force microscopy(AFM)show that the CDs have an amorphous structure and are of uniform distribution with sizes of ca.11-25 nm.In the chapter 3,five kinds of CDs-metal ion pairs as sensing elements to construct the fluorescent sensor array,and examined the ability of the fluorescent sensor array to detect seven kinds of thiols.The fluorescence array sensor not only can distinguish and identify the thiols with concentrations of as low as 1 ?moL·L-1,the same kind of thiol in the range of 1-10?moL·L-1,and mixtures at various molar ratios of two thiols,But also,the unknown thiol samples and the thiols in the practical samples were identified and distinguished.It is proved that the fluorescent sensor array has good analytical performance for thiols and can be used for the detection of practical samples.The sensing mechanism of the fluorescent sensor array was also explored in this chapter.Studies have shown that the fluorescence intensity of the CDs further quenched or enhanced after adding thiols depended on the type of metal ion which constituted the CDs-metal ion pairs.